An essay on dew and several appearances connected with it


William Charles Wells
Title PagePage 1Pages 2-3Page 146

In this great classic of meteorology, Wells' most important contribution was his meticulous study of the formation of dew and the correct interpretation of his data. he proved that dew is neither invisible rain, falling from heaven, nor 'sweat' from plants, but is due to condensation from air in contact with objects that have been cooled by radiating their heat into the cloudless night sky. he showed experimentally that dark substances collect more dew than pale ones, that poor conductors of heat collect more dew than good conductors, and that windless nights favor dew formation as the air is allowed to remain in contact with cooled objects long enough to deposit moisture. For this important work, Wells was awarded the Rumford Medal of the Royal Society. His researches on the subject were of major importance in the development of the science of ventilation, particularly in its relation to relative humidity and the influence of the latter on the comfort of the occupants of factories, ships, and theatres.